Neuroplasticity
by Evenlodes Friend
Summary: Sherlock's new experiment in Neurology involves John removing his shirt. A one-off adventure in gratuitous fluff.  Please review.


**Neuroplasticity**

They fall through the door, laughing. Too much beer and too much success. Two armed robbers in the cells, and Lestrade's face a picture.

'Did you see his face?' Sherlock's long limbs have loosened with the alcohol.

'Tea,' says John. He disappears around the partition into the kitchen. 'Want one?'

'Yes,' Sherlock calls back. He can hear the doctor crashing about with the kettle and the tea caddy. He hears the crump of the fridge door opening. There is a pause. John reappears, holding fat plastic discs in his hand.

'Sherlock.' Accusingly.

'What?' Sherlock plumps down in the sofa and opens a crumpled old newspaper. John has been doing the crossword.

'Petrie dishes, Sherlock,' he says. 'In the fridge.'

'Experiment.' Sherlock takes a pen out of his breast pocket and completes the puzzle, scoring the nib so deeply into the newsprint that he almost tears it in his irritation that his flatmate should be so stupid as to fail to get the childish clues.

'You promised me,' John says petulantly. 'No more botulism in the fridge.'

'Its not botulism,' he says, clicking the top of his pen to stow the nib with his thumb. He looks up. 'It's E Coli.'

'The milk is in there, Sherlock,' John complains.

'Alright, I'm sorry. I won't do it again.'

John sighs wearily. They both know the little ritual. Of course he will do it again. No doubt it will be necessary. And then he will apologise to John when he does.

The kettle is boiling, belching steam. Sherlock tosses the paper aside, and finds himself staring at the bank TV screen. He can hear Watson filling up the mugs. There is that nagging feeling again, like frost forming on his windpipe. He has not said what he needs to say. It won't wait any longer. He gets up.

Watson is sniffing the milk with a wary expression.

'Would you help me with an experiment?' Sherlock asks him. He doesn't turn around.

'Not if it involves petrie dishes in the fridge.'

'Something much simpler.'

'Depends on what you want me to do.' Watson hands him a mug of pointedly black tea, but he abandons it immediately on the toast crumb gritted draining board.

'Would you show me your scar?'

There. He has said it. The words hang between them. John stares at him. The thing they never bring up. John's wound.

They are both suddenly intensely sober.

'Why?' Watson's eyes have taken on that hard cast they always do when the subject of his injury, or the war, comes up.

'To test a hypothesis.'

'Which is?'

'I'll tell you if it is proven. Not worth bothering you with otherwise.'

John Watson puts down his mug. Sherlock can see he is thinking, struggling with himself. There is a little furrow that develops at the corner of his mouth at such moments. Sherlock finds his own heart is beating fast. He discovers he is afraid that John will turn him down. If he does, it will be the first time. It is an option that never occurred to the consulting detective.

It is a small chance.

Still, the statistical knowledge is little comfort.

John's hand twitches, hesitates. Then rises. The short, solid fingers fiddle with his buttons.

Sherlock takes a slow, deep breath and prepares himself. He cannot watch as Watson divests himself of the checked shirt. Partly because it is such an intrusion, and partly because he cannot bear the suspense. After all, what if he is right? He grips the worktop beside him, the better to concentrate on the war going on inside himself. Does he really want to know?

'Sherlock.'

John's voice shakes him out of his frenzied thoughts. The former soldier is standing there, his upper body naked and vulnerable, on the opposite side of the kitchen they share with such acrimony. He is holding his shirt by the collar, arms at his sides, not knowing quite what is expected of him.

Sherlock's stomach turns over. He becomes aware of a strange electrical buzzing at the back of his neck, a slight chill even. He paces around the kitchen table to make a closer examination.

Watson's body is the compact, solid shape typical amongst successful frontline soldiers, the lower centre of gravity being an advantage in combat situations. His torso has clearly been intensely muscular in the past but, with lack of use, has softened. His breasts are slightly loose, the nipples hard brown nubs from the cool air, with hair between them, slightly ginger in tone.

Drawing closer in the harsh kitchen light, Sherlock can see the detail of the scarring on the left shoulder, the shiny, puckered skin, the deep pit in the pectoral muscle. He peers carefully, taking it in, holding his breath so that he can register all the data pumping in through his senses. He had not expected this much damage.

'Is there an exit wound?' he whispers.

'No. Lodged in the interior of the scapula.'

Sherlock's heart is thudding against his ribs now as he tries to hold his nerve. His fingers shake as he reaches out to very lightly brush the edge of what is clearly an area of skin graft close to the depression. The good flesh of John's shoulder and breast constricts into gooseflesh when the detective touches him.

Sherlock's tilts his head to one side, very slowly. He is close enough to John to feel his breath on his cheek, to smell the sugar and cinnamon smell of his synthetic deodorant, to see the throbbing of blood in the artery close to the surface of his neck. That delicate pulse, clinging to life by such a gossamer thread, is hypnotic. Then he recollects himself, clears his throat and turns away.

In the living room, the air is warmer. The curtain on one of the windows is still open. He stands there, looking down onto the street, his cheeks burning.

'Sherlock?'

John has come in from the kitchen but Sherlock dare not turn round, dare not speak in case emotion declares itself in his voice.

'What's this about?'

The doctor is close now, and Sherlock becomes aware of a hand resting on his shoulder.

'Neuroplasticity,' he says, and his voice sounds unsteady.

'The capacity of the brain to compensate for damage by forging new neural pathways,' John says. 'First noted in stroke patients. What's your point?'

Sherlock knows he can't turn round. 'Have you ever seen the MRI scan of a sociopath?'

'Not that I can remember.'

'But you've seen MRI scans of stimulated brains?'

'Plenty of brain injury cases, yes. Why?'

'That of a stroke victim, for instance, shows distinctive dark areas demonstrating inactivity in specific brain areas.'

'Related to language and motor control, yes.' John's voice has taken on a note of worry.

'That of a sociopath will show inactivity in various areas related to emotion and empathy,' Sherlock explains.

'What's your point?'

'My point is,' says Sherlock, turning his head slightly because he wants the comfort of seeing the shape of Watson's gentle face from the corner of his eye, 'that I have recently begun to experience certain phenomena which lead me to the hypothesis that I am forming new neural networks, enabling me to experience empathy and other, non-self-focussed, emotions.'

Watson's grip on his shoulder strengthens. Sherlock turns a little more, sure that John will see the tears slicking his face.

'I was not sure this was the case until I saw your injuries. I experienced a…' He struggles to find the words. '…A dreadful distress for your suffering, for the pain you have experienced. And the desire to alleviate it. I also find myself aware of a desire to make you happy. I experience sadness when you are not in my presence, and a sense of excitement when I expect your return. I find myself elated when you are happy, and sad when you are not.'

He screws up his courage and finally manages to look the doctor in the face. What he sees amazes him. Not ridicule, or an expression of detached scientific interest, but tenderness.

'Love,' he says.

'What?'

'The name for the collection of feelings you are experiencing. It's called love.' Gently he takes Sherlock in his arms, and holds him. Sherlock rests his forehead on John's naked shoulder, feeling the cool flesh, and weeps softly.

* * *

><p>This was originally the first part of a longer story, but I think it stands alone perfectly, so I'm leaving it at that. The aim was to get Sherlock's idiom right, to examine how a man who views the world in scientific, dispassionate terms, would try to understand the advent of experiencing feelings. Posted in response to enthusiastic demands from my friend Clare. Please, let me know what you think, I am very needy when it comes to reviews!<p> 


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